Originally Posted by
Saddle Up
Carbon fibre frames are about ride quality and efficiency not necessarily about outright speed.
But there isn't a problem with ride quality unless you are using narrow high pressure tyres. And the efficiency argument is based on lies about frame flex and energy losses.
When you construct a frame using metal tubes and want it to have decent ride quality some vertical compliance is built into the frame. The problem is lateral compliance cannot be eliminated. When you stand on it climbing a hill for instance the force at the crankset also causes the frame to twist slightly and when it rebounds it propels the bike forward, this is the lively feel fans of steel frames talk about.
Yes. What's the problem with this?
Carbon fibre frames can be engineered to behave however the designer wants it to. They'll normally have over built headtubes, bottom brackets and chainstays for lateral stiffness so that there is less power loss from the rider.
There is no power loss from frame flex. It's a myth. (
www.bikethink.com/Frameflex.htm) As you just said - without seeming to understand your own words -
the energy from flex is stored and released. This is actually a desireable characteristic because it evens out power transmission from the frame, prevent components that lose energy when they flex from being overloaded. (
www.kirkframeworks.com/Flex.htm)
What you put in comes out. There's nothing quite like standing on a carbon fibre frame and feeling the forward thrust with every pedal stroke. Why should efficient power transfer be available to road bikers only?, nonsense!!.
This is utter bollocks and convincing only to someone who doesn't understand engineering. You've been trained to recite industry marketing material without understanding the engineering underneath it. In fact, even the bike industry's own
PR stunts show that you say isn't true - when I have more time later I'll discuss the notorious steel vs carbon test in the August's Procycling.
Hybrid riders are also the engine suppling the power. You don't need to be an open road rider to be a serious cyclist. The toptube and seat stays can be more more delicate for vertical compliance and offer a smooth as butter ride. Carbon fibre offers the best of both worlds. I would argue that with the quaility of city streets compared to our highways carbon fibre is more useful on a hybrid rather than on a racing machine being ridden along the smooth shoulder of a highway.
Once again: bollocks. 30mm tyres instead of 28s will make more difference than all the carbon in the world. Let alone 38s instead of 23s.
I find BF is way to full of opinion not fact.
You seem to be having a
hypocrisy detection malfunction: you haven't given a single fact - just unsourced and unreasoned opinions. The best modern engineering techniques - the ones used to design bikes - and first rate frame designers - including Keith Bontrager - say that you're wrong. Working in a bike store means that you know how to work a till and (hopefully) tune a derailer. It doesn't make you an engineer or expert on materials!
These top of the line carbon hybrids from companies like Trek, Specialized etc are so much fun to ride. They accelerate like crazy and have a ride quality that aluminum bikes simply can never match. Worth every penny. Let the detractors ride their janky bikes.
Again, bollocks. Power meter readings and instrumented tests on steel and carbon frames say there is little to no difference. (See that issue of Procycling.) Some riders perceive a large one because the carbon frame is stiffer which provides more proprioceptive feedback, which the brain interprets as "Faster!" But if you knew the first thing about frame design you'd know that rider's subjective impressions are usually wrong - I suggest you read Keith Bontragers discussion of frame flex for this reason also.
And please - don't whine about other people giving opinions rather than facts when you can't source a single one of your claims.
Let me ask you these three questions - all of which require
factual answers instead of buy-a-more-expensive-bike-bs
- What do you tell customers about the risk of crash damage when they buy a CF bike? Because I'll bet that most people here weren't warned.
- How much extra power, as a total of the percentage, do you think is lost to flex in a metal frame as opposed to a CF? Assume pro riders riding hard to get a worst case. What's your evidence for your figure?
- How much less speed on the flat, pedalling at, oh, 200W, do you think this power loss equals?
I should warn you, to be fair, that I have answers to both of the last two questions, and they say that
everything you said was ill-informed nonsense - although its the sort of nonsense thats helpful if your job is to get people to waste more money and increase your commission.